This history of American occupational medicine and hygiene during the years 1870 to 1935 focuses on Dr. Alice Hamilton's career as field investigator, coordinator of laboratory research, educator, business consultant and organizer of the discipline of industrial toxicology. The project surveys late nineteenth century studies of occupational diseases and traces Hamilton's activities as a means to describe and analyse the different early twentieth century institutions which studied occupational hygiene and attempted to change health conditions in the workplace. State and federal agencies, corporations and universities chose different approaches to the complex problems posed by occupational hygiene, and Alice Hamilton experienced the restrictions and options each imposed on investigators. A study of Hamilton's career and the experiences of her fellow occupational physicians offers insight into twentieth century labor history, the history of technology, the history of government science policy and the history of public health and medicine.